Flow limiting valve



Sept.v 17, 1963 w. K. GULlcK FLOW LIMITING VALVE Filed Sept. 19, 1960 K RM M mm m E r WGW i K 7 M t 7 L 2 6 a a e 4 4 m w/W 032 4 2 33 Y ,wf 2 2 f W B M \\X alrhm.. L im; I3.- mw .l n. I. ifm \21|\l l .f//l I M W/ a p J 0 Ama 2 2 Ww 3.@

vili! il V United States Patent O 3,103,950 FLOW LIMITING VALVE William K. Gulick, Glendale, Ohio, assigner to the United States of America as represented by the Secretary of the Air Force Filed Sept. 19, 1960, Ser. No. 57,083 2 Claims. (Cl. 137-494) This invention relates to flow limiting valves or more particularly to .a valve for maintaining a constant flow of liuid under widely varying conditions of temperature and viscosity. Y

It is desirable, and frequently necessary, to supply a constant flow of uid whether it be gas or liquid. In the case of an airplane the fluid supply for a hydraulic system may be subjected to temperatures of 65 F. to 350 F. which greatly affects the viscosity of the fluid.' Unless means is provided to assure an even flow of fluid the hydraulic system will receive too little ow when the supply is cold or too much when the supply is hot.

There is no known `device which will automatically maintain a constant flow of iluid in such a system when subjected to such extremes of temperature or viscosity. A device `or system is indicated, therefore, which is sensiltive `to viscosity and which Will operate reliably and automatically in fluids subject to such extremes. Several possible solutions to the problem suggest themselves, such `as the use of motors actuated by thermocouples or temperature sensitive devices, such as springs, bimetallic mechanisms, contained gases or iiuids. All of these approaches appear unsatistactory as being complex, heavy, unreliable, expensive and limi-ted yas to range.

It is an object of this invention, therefore, to provide a simple, reliable device for maintaining a constant flow of fluid regardless of its viscosity.

It is a further object to devise such a device which is inexpensive, light in weight Iand easily attached in the line to be regulated.

It is a still further object to furnish ya viscosity sensitive device which will regulate the flow of a iluid through it at a constant level under extreme variations of temperature and viscosity of the uid.

The above objects are met by the present invention which consists essentially of a cylinder interposed in the line to be regulated which employs a capillary tube as defined by Poiseuilles law, yan orice as defined by Bernoullis law (both in compliance with Reynolds criterion) which determine the position of Va piston biased by a spring to regulate Ithe flow of fluid around said piston and through said orice according to .the viscosity of the iiuid.

The above and still other objects, advantages and features of my invention will become apparent upon consideration of -the following detailed description of one embodiment thereof, especially when taken in conjunc- 'tion with the accompanying drawing, in which the ligure7 is a sectional view showing the essential parts of the valve assembly.

In the drawing 10 represents a cylindrical shell, or Ihousing, in which is fitted a cylinder lining 16. A cylinder 17, bored in its upper portion to house a piston 18, and connected with `an inlet 13, is held in the said housing by Van entrance fitting 12 and yan exit itting 14 threaded to screw into the ends of said housing. Oil rings 30 are provided to prevent the escape of lluids. A passage 2S between the outer surface of cylinder 17 and the inner surface of cylinder lining 16 connects entrance port 13 with lan exit port 15 through a metering orifice 32. The lower end of cylinder 17 is counter bored to form a chamber 21 housing a spring 20 held in position by a threaded plug 34 and a spring guide 24 which abuts against piston 18. Plug 34 is bored to proice vide a capillary entrance 26' to chamber 21 from the exit port 15 and is threaded into cylinder 17 to serve as a stop and adjustment for the pressure of spring 20. At the bottom of cylinder 17 is an exit orifice 36 which serves to connect passage 28 with exit port 15. Through the piston 18 is a capillary bore 22 which connects the upper face of piston 18, designated A1, to the lower face of said piston, and designated A2. Capillary 22 is designed to pass no liow, or very little ow, at extreme high viscosity conditions of the liuidand permits increasing oW with decreasing viscosity.

In operation assume -a constant pressure of a fluid in entrance port 13 yat a temperature of 65 F. At this temperature the fluid is at extreme viscosity.

Piston 18, which is cylindrical in shape having equal l areas at A1 and A2, is fully displaced in the direction of the arrow, thereby compressingspring 20l when lluid pressure is applied to entrance port 13. The capillary 22, through the piston `18, is designed such that there exists no fluid flow, or very little flow, through it at low temperature and high viscosity of the fluid. All llow must pass through oriiice entrance 32, metering cylinder passage 28 and limiting orifice 36. As the temperature increases and the viscosity decreases flow begins through the lirst capillary 22 creating a iluid pressure in spring chamber 21. This pressure tends to move piston 18 up thus closing orifice entrance 32 and restricting the flow of fluid through said entrance orifice, metering passage 28 and limiting orifice 36. Since the pressure on A1 is constant and the pressure on A2 is ch-anging with the Viscosity of the fluid due to the flow of fluid through capillary 22 the pressure on A2 plus the force of spring 20 tends to move the piston up closing orifice entrance 32. Since the spring 20 exerts la constant pressure on the piston 18, the amount of flow is determined by the flow through capillary 22 which is dependent on the viscosity of the fluid. The orifice 32 is designed to pass the desired flow minus the liow through the capillary 22 and capillary 26 out through exit port 15. The spring stop and orifice adjustment plug 34, threaded into the metering cylinder 17, serves to adjust the spring rtension as well Ias metering oriiice 32.

Thus a simple, straightforward device for limiting the flow of a lluid of changing viscosity has been provided. It has only one moving part, the piston, unless movement of the spring in compression Iand decompression is considered a moving part. It may be constructed entirely of metal to withstand the high pressures encountered in airplane hydraulic systems land high temperatures. It is tolerant of vibration encountered in air-. planes and in fact its action is helped by such Vibration..

It is to be understood that the above `described arrangement is merely illustrative of the applications of the principles of the invention. Numerous other arrangements may be devised by those skilled in the art without departing from the spirit and scope lof the invention.

What I claim is:

1. A valve for limitingY a llow of a fluid in a hydraulic system having a constant pressure comprising,

a housing having a passageway therethrough, o-ne end of said passageway being designated as an inlet port, the other end being designated as an exit port,

means in said passageway `adjacent said inlet port forming a cylinder,

a piston adapted for movement in said cylinder, said means including a chamber behind said cylinder,

spring means within said chamber for biasing said piston toward said inlet port,

said housing land cylinder forming means defining an annular passageway having openings connecting said cylinder and inlet with said exit port, the opening in said cylinder forming a metering lorifice controlled bythe position of said piston, and

capillary means connecting said inlet and said chamber for introducing a pressure aiding the force of said biasing spring to cause a closing of said metering orifice by said piston when the viscosity of the uid decreases a predetermined amount.

2. A valve for providing a predetermined, constant iiow `of a uid in a hydraulic system having a constant pressure regardless of ythe viscosity of 'the fluid comprisms,

a housing having a passageway therethrough, one end of said passageway being designated as an inlet port, the other end being designated as an exit port,

means in said passageway adjacent said inlet port forming a cylinder,

a piston adapted for movement in said cylinder, said means including a chamber behind said cylinder,

spring means within said chamber for biasing said piston toward said inlet port,

said housing and cylinder forming means defining an annular passageway having openings connecting said cylinder wit-h said exit' port, the opening in said cylinder forming a metering orifice controlled by the position of said piston,

capillary means in said chamber for connection Iof said` chamber with the exit port portion of said passageway, and

capillary means through said piston of a diameter to prevent liow of fluid therethrough under extreme, high viscosity conditions and to permit a ow of iluid as viscosity conditions decrease in order to augment; the pressure in said chamber to aid said spring in biasing said piston to close said metering on'ce.

References Cited in the iile of this patent UNITED STATES PATENTS 2,164,669 Thomas July 4, 1939 2,225,880 Montelius Dec. 24, 1940 2,243,011 LOrange May 20, 1941 2,317,743 Duckstein Apr. 27, 1943 2,966,170 Raulins Dec. 27, 1960 

1. A VALVE FOR LIMITING A FLOW OF A FLUID IN A HYDRAULIC SYSTEM HAVING A CONSTANT PRESSURE COMPRISING, A HOUSING HAVING A PASSAGEWAY THERETHROUGH, ONE END OF SAID PASSAGEWAY BEING DESIGNATED AS AN INLET PORT THE OTHER END BEING DESIGNATED AS AN EXIT PORT, MEANS IN SAID PASSAGEWAY ADJACENT SAID INLET PORT FORMING A CYLINDER, A PISTON ADAPTED FOR MOVEMENT IN SAID CYLINDER, SAID MEANS INCLUDING A CHAMBER BEHIND SAID CYLINDER, SPRING MEANS WITHIN SAID CHAMBER FOR BIASING SAID PISTON TOWARD SAID INLET PORT, SAID HOUSING AND CYLINDER FORMING MEANS DEFINING AN ANNULAR PASSAGEWAY HAVING OPENINGS CONNECTING SAID CYLINDER AND INLET WITH SAID EXIT PORT, THE OPENING IN SAID CYLINDER FORMING A METERING ORIFICE CONTROLLED BY THE POSITION OF SAID PISTON, AND CAPILLARY MEANS CONNECTING SAID INLET AND SAID CHAMBER FOR INTRODUCING A PRESSURE AIDING THE FORCE OF SAID BIASING SPRING TO CAUSE A CLOSING OF SAID METER- 